Generally, in micro fractional ablation that has been recently developed as a clinical method for dermatological treatment, a micro laser beam is irradiated in various patterns on a certain area of the skin. At this time, a handpiece tip should be in contact with the skin so that the size of the laser beam can be maintained accurately. Various contact sensors have been used to determine whether the handpiece tip is in contact with the skin.
Referring to FIG. 1, a conventional laser beam handpiece comprises a laser fiber 12 made of sapphire to irradiate laser beams, which are output from a laser beam output device (not shown), in a handpiece body 10; a collimating lens 14 for converting the laser beams irradiated from the laser fiber 12 into collimated light; a reflector 16 for changing a beam path of the laser beams output through the collimated lens 14; and a focusing lens 18 for focusing the laser beams reflected by the reflector so that the laser beams can be irradiated on a position. One of contact sensors to be employed at this time is an electrically operated contact sensor in which at least two electrodes 19 electrically insulated to each other are mounted at certain portions on a handpiece tip (not shown) and a predetermined voltage is applied between the electrodes. When the electrodes are in contact with the skin, a certain electric current flows through the skin. The electric current is measured to check a state where the electrodes are in contact with the skin. Only when the handpiece tip is in contact with the skin, a laser can be oscillated and micro laser beams can be irradiated on the skin.
However, in the method of measuring an electric current flowing through a human body, the amplitude of an electric current flowing when two electrodes are in contact with the skin varies according to persons and skin resistance depends on parts to be treated or skin conditions. As a result, there is a problem in that it takes much time to differently deal with respective conditions.